Breath analyzers according to the state of the art are designed for specific situations and application areas. A variety of products exists for applications in screening, clinical diagnostics, and for evidential purposes for the determination of breath alcohol concentration. For the latter category, high priority requirements are measuring accuracy and specificity. For screening purposes, speed of response and simplicity for the test person are more important, especially when the fraction of positive response, i e concentration exceeding a certain threshold value, is expected to be small. This is the case in testing of sobriety of vehicle drivers, including alcolocks or similar devices.
In evidential instruments and qualified diagnostic instruments, infrared spectroscopy is being used as the measuring principle, resulting in very high accuracy and specificity. For screening purposes, simpler sensors based on catalysis, e.g. fuel cell or semiconductor elements, are being used. They are advantageous with respect to production cost, but have drawbacks when it comes to reliability. The catalytic function is difficult to control, and the sensors have limited life time. In most breath analyzers the test subject is required to deliver forced expiration into a tight-fitting mouthpiece. The procedure is time consuming and problematic to persons with impaired respiratory function.